Electric measuring instrument.



No. 657,984. I Patented Sept-.18, I900.

J. HARRIS.

ELECTRIC MEASURING INSTRUMENT (Applicatiun filed July 20, 1899.) (NoModel.) 2 Sheets-Sheet I. V

1n: ucam's pains m. mroumo WASHIN No. 657,984. I V Patented Sept. l8,I900. J. HARRIS. ELECTRIC MEASURING. INSTRUMENT.

(Application filed July 20, 1899.) (No Modl.) 2 Shaets$heet 2.

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UNITED STATES PATENT OFFIC JESSE HARRIS, OF LYNN, MASSACHUSETTS.

ELECTRIC MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 657,984, datedSeptember 18, 1900.

Application filed July 20, 1899. semi No. 724,500. we model.)

10 air? whom it may concern:

Be it known that I, JESSE HARRIS, a citizen of the United States,residing at Lynn, Massachusetts, have invented certainnew and usefulImprovements in Electric Measuring Instruments; and Idoherebydeclare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,and to the letters and figures of reference marked thereon, which form apart of this specification.

The object of my invention is to provide a new and improved electricmeasuring instrument.

Figure 1 shows a top plan View of my indenominate an angular coil, orsolenoid 7-' 't'. e., a loop of wire wound and insulated in the usualmannerthe loop being so'formed that the opening a atone end is greaterthan the opening 6' atthe opposite end, forming what Idenominate anangular coil or angular solenoid, notwithstanding the opening may or maynot be actually angular. coil receives the current to be measuredthrough conductors 11 and 12. g

The moving parts consist ofthe arm 6 and the pointer 5, which arepivotally attached to a frame 3 by means of an adjustable pivot orpivots 4 4, the points of said pivots preferably working in jewels setin the ends of the shaft, to which shaft is attached the coiled springs13 and 13 or other operative resilient devices, the outer ends of saidsprings being so attached to the frame 3 that their resilience willexert a certain amount of resistance to the rotation of the'shaft. Tothis shaft is also attached the pointer 5, having its free end bifurcated, preferably, so as to have the two indexes in order that thereading of the scale may be facilitated.

To the shaft is also at- This tached a homogeneous arm 6, having a pieceor pieces of soft iron 6' attached to its outer extremity and having anadj Listing-weight 10 arranged to be moved along the arm as may bedesired. Directly under the bifurcated ends of the pointer 5 is secureda graduated scale 8, over which the pointer moves. To the pointer 5 andarm 6 is attached an airbrake B, consisling, preferably, of anon-metallic material and, as shown, a plate of mica. In the recess ofthe block 1 is a metal basepiate 9', to which is affixed the frame 3,and the coil is affixed there by means of ears or studs'9.

My instrument operates as follows: When the current to be measuredpasses through the coil 7, themagnetic flux becomes more dense at thenarrower end I) of the coil, and the homogeneous arm dis drawn more andmore toward this narrow end as the current increases, and thus swingsthe pointer 5 with it. As the arm 6 andpointer 5 swing by means of theshaft the rotation of the shaft is opposed by the springs 13 and 13',and when there is no current passing these springs force the pointer 5back to zero-point. The adjusting-weight ld acts as a balance, allowingthe weight of a'rm6 to'be centered on the shaft, so as to lessenfriction and maintain a balance of the moving parts in all positions,While air-brake B steadies the movements of the pointer, preventingthepointer from oscillating backand forth, as it would do if no means wereprovided to prevent it.

My instrument, then, may be described as consisting of a coil orconductor traversed by a current to be measured, the coil being a loopor solenoid wider open at one end than the other, as seen at 7, and soarranged and having a movable magnetizable body, as seen at 6 and 6, soarranged as to be within the influence of the said coil and to movedthereby by reason of the magnetic flux becoming more dense at thenarrower end I) of the coil and having means, preferably springs 13 and13, by which the pointer 5is brought to zero when no current flows, andan air-brake, as B, arranged so that as it moves against the atmosphereit steadies the motion of the pointer, the free end of the pointer5being ifurcated or having a plurality of ends or sights, so as to assistin reading the grad-uated scale, the error due to the parallax beingthereby corrected. It will be observed that my meter or measuringinstrument when so arranged will operate in a variety of positions andis not confined to being placed in any one position, as it will operatewhen laid upon a table either on its face or its back and when hung on awall perpendicularly or at any angle therefrom.

Having arranged my meter as seen in Fig. 1, in which form it is anammeter by reason of having used large wire for the winding of the field7-, it remains to be stated that my meter or measuring instrument may beeither a voltmeter or an ammeter by simply using different-sized wirefor the winding,as if large wire be used an ammeter will be produced,but if small wire be used, whereby the resist ance is raised, then avoltmeter results, and alternating as well as continuous currents may bemeasured.

I-Iaving described my invention, What I claim is 1. In an electricmeasuring instrument a coil or solenoid traversed by an electric currentto be measured, the coil or solenoid having a tapering opening and amovable homogeneous magnetizable arm or body within said opening, and anindicator; the arm and the indicator being arranged to be moved by theinfluence of the current and to be operative in any position, and havingmeans for bringing the indicator to zero when no current flows throughthe coil substantially as described.

2. In an electrical measuring instrument a revoluble shaft and ahomogeneous arm or body carried thereby, and a triangular coil orsolenoid, the homogeneous arm or body being arranged so that a portionthereof at least lies in the triangular opening in the coil or solenoidand having an index, all arranged so that when the index is at zero thearm or body rests at its greatest distance from the sides of the coiland as the indicator moves toward the higher readings the arm or bodyapproaches nearer to said sides and arranged to operate in a pluralityof positions substantially as described.

3. In an electrical measuring instrument a V-shaped open coil Within theopening of which lies a homogeneous magnetizable arm or body, said armor body being mounted on a shaft and having an indicator and scale forreading the movements of the arm and indicatorand a resilient device forcontrolling the return of the indicator to zero and opposing themovements of the arm or body against the force generated in the coilsubstantially as described.

4. In a measuring instrument a pointer or index provided With separatesights arranged to eliminate the error due to parallax substantially asdescribed.

5. In an electrical measuring instrument an angular-shaped open coil orsolenoid Within the opening of which is a homogeneous magnetizablemovable arm or body, said arm or body being arranged to be moved by theresultant force of a current passing through the coil and to move thearm from zero to higher readings, and having a resilient device arrangedto return the arm to zero when no current is in the coil, and having ascale and indicator arranged to indicate the movements of the arm and anair-brake arranged to steady the motion of the moving partssubstantially as described.

6. In an electrical measuring instrument an angular coil or solenoid andan arm, a portion of which at least, rests in the openingin the coil,and arranged to be horizontally deflected, and having a pointer arrangedto be moved or deflected in unison with said arm and a graduated scaleto which the pointer points as it moves substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

JESSE HARRIS.

WVitnesses:

W. M. BROWN, JAMES M. BROWN.

